A cyclic process of peptide design, peptide synthesis and peptide conformation study is used to refine methods of determining oligopeptide conformation in solution and predicting it from amino acid sequence. The principal technique for conformation study is high resolution nuclear magnetic resonance, coupled with model building and empirical calculation of conformation. Correlations are made with optical (ORD, CD) data, crystallographic results, and chemical reactivity. The peptides to be used in this work will be (a) synthetic cyclic oligopeptides, chiefly those containing one or more basic amino acid side chains, (b) linear oligopeptides, which it is desired to design so that the chain folds into strongly preferred conformations other than helical, and (c) isotopically labeled peptides obtained by cleavage of the algal protein phycocyanin.